1. Field of the Invention
The present general inventive concept relates to a projection-type 3-dimensional (3-D) image display, and more particularly, to a projection-type 3-D image display to achieve a small size by realizing a 3-D image using a single projector and to improve a resolution of the 3-D image.
2. Description of the Related Art
Generally, a 3-D image is realized through two eyes of a human being using the principle of stereo visual sense. A binocular parallax, which is generated because left and right eyes are located about 65 mm apart from each other, is an important factor in producing a cubic effect. 3-D image displays are divided into displays using glasses and glassless displays. Glassless displays obtain the 3-D image by separating left/right images without using glasses. The glassless displays are divided into parallax barrier type displays and lenticular type displays.
The parallax barrier type displays alternately print images that should be seen respectively by the left and right eyes in the form of a vertical pattern or a photo (in order to see the printed image using an extremely thin vertical lattice column, i.e., a barrier). By doing so, a vertical pattern image that is provided to the left eye and a vertical pattern image that is provided to the right eye are distributed by the barrier and images at different viewpoints are seen by the left and right eyes, respectively, whereby a stereo image is perceived.
A projection-type image display enlarges an image formed by a display element using a projection lens unit, projects the enlarged image on a screen unit, and realizes a 3-D image using a left/right eye image separation unit provided to the screen unit. FIG. 1A is a schematic view illustrating a conventional projection-type image display. The conventional projection-type image display includes a first projector 10 and a second projector 20 and produces a 3-D image by separating images into first images from the first projector 10 and second images from the second projector 20 and sending the first and second images to a right eye (RE) and a left eye (LE) using a screen unit S, respectively.
The screen unit S has a parallax barrier 25 in order to separate the first and second images produced by the first and second projectors 10 and 20 for the RE and the LE, respectively. As illustrated in FIG. 1A, the parallax barrier 25 has slits 26 and barriers 27 arranged in an alternate manner. The images from the first and second projectors 10 and 20 are separated into the first images for the RE and the second images for the LE by the slits 26 to form the 3-D image.
FIG. 1B illustrates the first and second image R and L formed by the conventional projection-type image display of FIG. 1A. Since the first and second images R and L are formed and blocked through the slits 26 and the barriers 27, respectively, the second images L are formed at even-numbered lines only and blocked by the barriers 27 so that black lines K are formed at odd-numbered lines, as illustrated in FIG. 1B. Similarly, the first images R are formed at the odd-numbered lines only and blocked by the barriers 27 so that the black lines K are formed at the even-numbered lines.
Accordingly, a resolution of a display on the whole, as well as a brightness of a 3-D image, deteriorates. Further, since two projectors are used in order to produce the first and second images R and L, a volume of the device is large, not meeting consumer demand for a device having a small size.